Search results for "SSB"
showing 10 items of 537 documents
Time integral and time differential Mössbauer measurements on [57Co/Mn(bipy)3](PF6)2
1994
The Mossbauer emission spectra of nucleogenic iron(II) complexes with a low spin (LS) ground state show two metastable iron(II) high spin (HS) states at low temperatures. In order to identify these metastable HS states, the compound [57Co/Mn(bipyridine)3](PF6)2 has been studied by time differential Mossbauer emission spectroscopy (TDMES) and optical lifetime measurements of excited electronic states in the corresponding Fe-doped Mn compound. The lifetime of one of the HS states of the nucleogenic iron(II) determined by TDMES has been measured to be the same as the lifetime of the laser-excited iron(II) electronic state.
Layer formation on silicon steel by processing in H2/H2O at elevated temperatures
1992
Silicon steel (Fe-3wt%Si), as used for transformers and generators, has been annealed in wet hydrogen at elevated temperatures. The composition, sequence, and thicknesses of the layers found by conversion electron Mossbauer spectroscopy (CEMS) and Auger electron spectroscopy (AES) depth profiling for a 10 minutes anneal in different atmospheres are reported. In the range from 500°C to 720°C we observed carbide formation, indicating that the decarburization is hindered. Above 800°C, the layers consist of fayalite or of fayalite and iron oxides, depending on the oxygen potentialaO. At 843°C, the onset of iron oxide formation was found ataO=0.33.
Anodic layers formed on steel in phosphate buffer solution
1986
In-situ gamma scattering and ex-situ conversion electron Mossbauer, and Auger spectroscopy were applied to investigate anodic layers on steel. Samples treated in the active potential range in phosphate buffer solution show a Fe(II)-phosphate deposit on the surface. After treatment in the passive potential region, only Fe3+was found to exist in the oxide layer. The passive layer does not consist of stoichiometric oxidic phases.
Iron-containing phases in metallurgical and coke dusts as well as in bog iron ore
2017
Abstract Several samples of dusts from steel and coke plants (collected mostly with electro filters) were subjected to the investigation of content of mineral phases in their particles. Additionally, sample of bog iron ore and metallurgical slurry was studied. Next, the magnetic susceptibility of all the samples was determined, and investigations of iron-containing phases were performed using transmission Mössbauer spectrometry. The values of mass-specific magnetic susceptibility χ varied in a wide range: from 59 to above 7000 × 10−8 m-3·kg−1. The low values are determined for bog iron ore, metallurgical slurry, and coke dusts. The extremely high χ was obtained for metallurgical dusts. The …
Molecular tunneling and pumping effects in low temperature MBCO recombination
1992
Recombination of carbonmonoxide after photodissociation has been studied by Mossbauer spectroscopy at 4.2K and in the low temperature region, where tunneling effects play an important role in rebinding. We interpret the kinetic results in terms of a radiationless nonadiabatic multiphonon transition, which leads to a uniform description for all temperatures. Prolonged illumination at low temperature results in pumping into long-living states.
Exchange-coupled Fe-X-Fe model compounds for certain iron proteins
1988
X-ray structure studies, Mossbauer experiments and magnetic susceptibility measurements were used in connection with molecular orbital calculations to monitor structurally induced changes of electronic and magnetic properties in exchangecoupled [Fe2S2 (SR)4]2- and [Fe2OCl6]2- anions.
Recombination studies of photodissociated MbCO by Mössbauer spectroscopy at low temperatures
1990
Rebinding of carbonmonoxide to myoglobin after photodissociation has been studied by Mossbauer spectroscopy at 57.6 K and below for up to 9 days. The time dependence is reproduced by a set of exponentials representing a distribution of activation enthalpies. A shift to smaller values of these activation enthalpies and of the preexponential factor compared to optical studies at higher temperatures has been observed as well as pumping into long-living states.
Mössbauer investigations on glass-forming organic liquids
1992
Glycerol forms a molecular glass near 180K. Fe2+ dissolved in glycerol allows the study of the dynamics of the system by Mossbauer spectroscopy. Recently it has been shown that the Mossbauer spectra can be understood in a way consistent with the results of dielectric and ultrasonic viscoelastic relaxation measurements. A jump diffusion model of Sinqwi and Sjolander with a jump rate distribution according to Davidson and Cole allowed us to fit the Mossbauer spectra of Fe in glycerol. First attempts to compare mode coupling theory with Mossbauer spectra are reported.
Dynamics of protein-water systems revealed by Rayleigh scattering of Mössbauer radiation (RSMR)
1990
A critical review of recent studies of protein dynamics by the RSMR technique is given. The main approximations in quantitative analyses of RSMR data are discussed and conclusions about dynamical properties of protein and interprotein water, deduced from experiments, are described.
Gamma-X-ray coincidence Mössbauer emission spectroscopy on57Co/CoO
1994
The time integral Mossbauer emission spectrum of a57Co/Co1−xO source (x ≈ 10−5) at RT consists of two single Lorentzian lines of an Fe2+ (76%) charge state and an Fe3+ (24%) aliovalent charge state. The spectrum measured by γ-X-ray coincidence spectrpscopy shows the same fraction of the aliovalent charge state, contrary to the expectation derived from the competing acceptor model as successfully applied by Tejada and Parak [1], who could explain the dependence of the formation of aliovalent charge states after the nuclear transformation on the stoichiometric parameterx. The consequences of this unexpected behaviour for the competing acceptor model are discussed.